Depth Distribution and Correlation Analysis of Ambient Noise Based on Underwater Acoustic Glider Measurements

There have been a lot of research results on the characteristics of ambient noise distribution with depth, but the correlation between the two is rarely reported. In order to reveal the cross-correlation between noise spectrum level and reception depth, three-day ambient noise measurements were conducted in the northern South China Sea using two underwater acoustic gliders. The acoustic system of underwater acoustic glider collects the noise signal in all stages except for the glider surface diving preparation stage and at the maximum working depth in the floating stage. The data processing results show that the ambient noise level fluctuates with the depth of glider platform, and it diminishes with the increase in receiving depth. At frequencies below 200 Hz, the cross-correlation coefficient between ambient noise level and depth is approximately 0.5, reaching a moderate correlation. At frequencies above 500 Hz, the correlation coefficient is greater than 0.8, indicating high correlation.